Thanks everyone. I think I'm going to wash a bunch of them in the sink with Dawn and rinse in vinegar to make sure all the chemicals are gone - mostly because I don't want lingering chemicals to stain the quilt down the road.
Not too worried about the flammability aspect as the quilt will stay in my home - not a gift - and as we don't smoke in the house I can't imagine it will be a problem. But I will certainly keep this in mind if I ever decide to make a string quilt as a gift for anyone.
I've been saving loads of them in my used Tide-Pod's containers. It's time to dig them out and use them!!